Practical Demonstration of Deep-Ultraviolet Detection with Wearable and Self-Powered Halide Perovskite-Based Photodetector

Enhanced Responsivity and Photostability of Cs3Bi2I9-Based Self-Powered Photodetector via Chemical Vapor Deposition Engineering

Lead-based halide perovskites have gained significant prominence in recent years in optoelectronics and photovoltaics, owing to their exceptional optoelectronic properties. Nonetheless, the toxicity of lead (Pb) and the stability concern pose obstacles to their potential for future large-scale market development. Herein, stable lead-free Cs3Bi2I9 (CBI) films are presented with smooth and compact morphologies synthesized via chemical vapor deposition (CVD), demonstrating their application as an UV photodetector in a self-powered way. The self-powered photodetectors (SPDs) exhibit remarkable characteristics, including a responsivity of 1.57 A W-1 and an impressive specific detectivity of 3.38 × 1013 Jones under the illumination of 365 nm at zero bias. Furthermore, the SPDs exhibit a nominal decline (≈2.2%) in the photocurrent under constant illumination over 500 h, highlighting its impressive long-term operational stability. Finally, the real-time UV-detection capability of the device is demonstrated by measuring the photocurrent under various conditions, including room light and sunlight at different times. These findings offer a new platform for synthesizing stable and high-quality perovskite films, and SPDs for advancing the development of wearable and portable electronics.

Enhance the responsivity of self-driven ultraviolet photodetector by (Al,Ga)N nanowire/graphene/PVDF heterojunction with high stability

Due to the low-power consumption, self-driven ultraviolet (UV) photodetectors have great potentials in a broad range of applications, such as optical communication, ozone monitoring, bio-medicine, and flame detection. In this Letter, it is pretty novel to enhance the photocurrent and responsivity of self-driven UV photodetectors by (Al,Ga)N nanowire/graphene/polyvinylidene fluoride (PVDF) heterojunction successfully. Compared to those of the photodetector with only nanowire/graphene heterojunction, it is found that both the photocurrent and responsivity of the photodetector with nanowire/graphene/PVDF heterojunction can be enhanced more than 100%. It is proposed that PVDF could maintain the internal gain by increasing the number of carrier cycles. Furthermore, this photodetector can also have a high detectivity of 5.3×1011 Jones and fast response speed under 310 nm illumination. After preserving for one month without any special protection, both photocurrent and responsivity of the photodetector with nanowire/graphene/PVDF heterojunction are demonstrated to be quite stable. Therefore, this work paves an effective way to improve the performance of photodetectors for their applications in the fields of next-generation optoelectronic devices.

Deep-Ultraviolet Transparent Electrode Design for High-Performance and Self-Powered Perovskite Photodetector

In this study, a highly crystalline and transparent indium-tin-oxide (ITO) thin film was prepared on a quartz substrate via RF sputtering to fabricate an efficient bottom-to-top illuminated electrode for an ultraviolet C (UVC) photodetector. Accordingly, the 26.6 nm thick ITO thin film, which was deposited using the sputtering method followed by post-annealing treatment, exhibited good transparency to deep-UV spectra (67% at a wavelength of 254 nm), along with high electrical conductivity (11.3 S/cm). Under 254 nm UVC illumination, the lead-halide-perovskite-based photodetector developed on the prepared ITO electrode in a vertical structure exhibited an excellent on/off ratio of 1.05 × 104, a superb responsivity of 250.98 mA/W, and a high specific detectivity of 4.71 × 1012 Jones without external energy consumption. This study indicates that post-annealed ITO ultrathin films can be used as electrodes that satisfy both the electrical conductivity and deep-UV transparency requirements for high-performance bottom-illuminated optoelectronic devices, particularly for use in UVC photodetectors.

Designing Ordered Organic Small-Molecule Domains for Ultraviolet Detection and Micrometer-Sized Flexible Imaging

Photodetectors displaying an ultraviolet (UV) spectral response window are typically based on wide-bandgap semiconductors that have long been dominated by inorganic materials that suffer from bottlenecks of low flexibility and a limited material family. Here, we synthesized a novel organic small molecule and controlled its crystallization to suppress leakage currents and facilitate separation of the carriers, and the relationship between the nanoscale phase separation morphology and the optoelectrical performance of the photodetectors is disclosed. Our optimized organic photodetector (OPD) presents a UV spectral response window, with superior self-powered responsivities of 45 mA/W (under 250 nm light) and 70 mA/W (under 300 nm light), outperforming the Si photodiode and rivaling other reported UV self-powered photodetectors. Finally, an imaging system was constructed to demonstrate the application potential of the OPD in UV flexible imaging with high-resolution arrays of 400 pixels × 400 pixels (5 μm × 5 μm per pixel), which could work in bent states and successfully output images of micrometer-sized objects.

Boosting Charge Utilization in Self-Powered Photodetector for Real-Time High-Throughput Ultraviolet Communication

Ultraviolet (UV) communication is a cutting-edge technology in communication battlefields, and self-powered photodetectors as their optical receivers hold great potential. However, suboptimal charge utilization has largely limited the further performance enhancement of self-powered photodetectors for high-throughput communication application. Herein, a self-powered Ti3 C2 Tx -hybrid poly(3,4 ethylenedioxythiophene):poly-styrene sulfonate (PEDOT:PSS)/ZnO (TPZ) photodetector is designed, which aims to boost charge utilization for desirable applications. The device takes advantage of photothermal effect to intensify pyro-photoelectric effect as well as the increased conductivity of the PEDOT:PSS, which significantly facilitated charge separation, accelerated charge transport, and suppressed interface charge recombination. Consequently, the self-powered TPZ photodetector exhibits superior comprehensive performance with high responsivity of 12.3 mA W-1 and fast response time of 62.2 µs, together with outstanding reversible and stable cyclic operation. Furthermore, the TPZ photodetector has been successfully applied in an integrated UV communication system as the self-powered optical receiver capable of real-time high-throughput information transmission with ASCII code under 9600 baud rate. This work provides the design insight of highly performing self-powered photodetectors to achieve high-efficiency optical communication in the future.

Recent progress in construction methods and applications of perovskite photodetector arrays

Metal halide perovskites are considered promising materials for next-generation optoelectronic devices due to their excellent optoelectronic performances and simple solution preparation process. Precise micro/nano-scale patterning techniques enable perovskite materials to be used for array integration of photodetectors. In this review, the device types of perovskite-based photodetectors are introduced and the structural characteristics and corresponding device performances are analyzed. Then, the typical construction methods suitable for the fabrication of perovskite photodetector arrays are highlighted, including surface treatment technology, template-assisted construction, inkjet printing technology, and modified photolithography. Furthermore, the current development trends and their applications in image sensing of perovskite photodetector arrays are summarized. Finally, major challenges are presented to guide the development of perovskite photodetector arrays.

Self-Powered UVC Photodetector Based on Europium Metal-Organic Framework for Facile Monitoring Invisible Fire

The effective use of a europium metal-organic framework (Eu-MOF) as a photoabsorber material has been reported. Using the advantages of Eu-MOFs including simple preparation, wide bandgap structure, and stability in the environment, a self-powered and high UVC-selectivity detector based on Eu-MOF nanoparticles was prepared with a simple device geometry. The as-fabricated photodetector was highly sensitive to 254 nm UV illumination without an external power supply. Accordingly, it exhibited a high UVC-to-UVA rejection ratio (I₂₅₄/I₃₆₅ ≈ 40) and UVC-to-solar rejection ratio (I₂₅₄/I_solar light ≈ 34), a fast response time of 98/122 ms, a comparable on/off photocurrent ratio (107.33), and superior stability. The self-powered Eu-MOF photodetector can detect and monitor UV emission from an invisible fire in an early state at room temperature, suggesting practical use as a potential optoelectronic device.

A Study to Improve the Performance of Mixed Cation-Halide Perovskite-Based UVC Photodetectors

Photodetectors convert optical signals into electrical signals and demonstrate application potential in various fields, such as optical communication, image detection, environmental monitoring, and optoelectronics. In this study, a mixed cation-halide perovskite-based ultraviolet C photodetector was fabricated using a solution process. The higher the mobility of the perovskite carrier, which is one of the factors affecting the performance of electronic power devices, the better the carrier diffusion. The on/off ratio and responsivity indicate the sensitivity of the response, and together with the detectivity and external quantum efficiency, these parameters demonstrate the performance of the detector. The detector fabricated in this study exhibited a mobility of 202.2 cm2/Vs and a high on/off ratio of 105% at a -2 V bias, under 254 nm light irradiation with an intensity of 0.6 mW/cm2. The responsivity, detectivity, and external quantum efficiency of the as-fabricated detector were 5.07 mA/W, 5.49 × 1011 Jones, and 24.8%, respectively. These findings demonstrate that the solution process employed in this study is suitable for the fabrication of mixed cation-halide perovskites which show immense potential for use as photodetectors.

High performance of CH3NH3PbCl3 perovskite single crystal photodetector with a large active area using asymmetrical Schottky interdigital contacts

The high performance of a Au/CH3NH3PbCl3 single crystal/Ag structured photodetector with a large active area.